Comparative evaluation of immunotherapeutic efficacy of BCG and mw vaccines in patients of borderline lepromatous and lepromatous leprosy

Abstract

Background: Even after 12 months of multi-drug therapy (M.D.T.) multibacillary (MB) therapy patients with high bacterial index (B.I.) continue to harbor dead bacilli and viable persisters, which lead to immunological complications such as recurrent reactions and late relapses, respectively. To achieve faster killing of viable bacilli and clearance of dead bacilli, various immunotherapeutic agents (vaccines and cytokines) are being evaluated as an adjunct to M.D.T. Aims and objectives. To evaluate the role of BCG and Mw vaccines in the immunotherapy of leprosy.

Materials and methods: Sixty untreated leprosy patients with a BI = 2 were randomly allocated to three treatment groups of twenty patients each. Group A patients received World Health Organization (W.H.O.) (12 months M.D.T.-MBR) and BCG intradermally (105 live bacilli/per dose). Group B patients were administered 12 months M.D.T.-MBR and Mycobacterium w (1 x 108) killed bacilli as first dose and 0.5 x 108 /dose in subsequent doses. Group C received 12 months M.D.T. MBR with 0.1 ml of normal saline as placebo. All the groups received 4 doses of vaccine or normal saline repeated at three monthly intervals. The patients were periodically monitored by clinical (Ramu's score), bacteriological (slit skin smear), and histopathological (skin biopsy) parameters, six monthly during and one year after completion of M.D.T.

Results: The mean reduction in clinical scores in BCG and Mw groups was significantly more when compared to controls. At 12 and 24 months, the patients in BCG group had significantly greater reduction in Ramu's score as compared to those in the Mw group. BI declined by 2.40 units/year in patients receiving BCG, 2.05 units/year in the Mw group and 0.85 units/year in the control group. Although the incidence of type 1 reactions was apparently more in the BCG and Mw vaccinated groups, the incidence of type 2 reactions, neuritis and development of new deformities was less as compared to the controls.

Conclusions: In our study, BCG exhibited slightly better and faster effect on bacteriological clearance and clinical improvement as compared to Mw vaccine in borderline lepromatous (BL)/ polar lepromatous (LL) patients with a high initial B.I., however, their effect on histopathological (decrease in GF) improvement was comparable. Both the vaccines were well tolerated. Immunotherapy can be a useful adjunct to the shortened (12 months) M.D.T. MB regimen to decrease the risk of reactions and relapses in highly bacilliferous BL/LL patients.